This study proposes to investigate the power and limitations of a classical conditioning paradigm in eliciting an elevation in interferon (IFN) titer and an enhancement of Natural Killer (NK) cell activity. The unconditioned stimulus (UCS) for this study is a Poly I:C injection, which will elevate both IFN titers and NK activity (the unconditioned response). The conditioned stimulus (CS) is camphor smell, a stimulus without effect on any known immune parameter. Preliminary studies from this laboratory have shown that we can obtain an enhancement of the NK activity using this conditioning paradigm, and we wish to examine whether IFN titers can be similarly conditioned. Further, we will determine the limits of conditioned enhancement of IFN levels and NK activity, we will optimize these elevations by modification of the schedule of CS/UCS pairing trials, and finally determine the pattern for extinction of these responses. Earlier in this century many results were published from Russian and European laboratories demonstrating both enhancement and suppression of a variety of specific and non-specific immune responses. These studies suffered from design problems, and reproducibility in other labs was inconsistent, thus this area of research fell into disfavor. Many recent efforts at conditioning immune responses have resulted in a slight suppression of both ongoing antibody responses and a graft-vs-host response. This study is unique in that we have successfully produced an enhanced NK cell response to a CS, a result which may prove to be an initiated response in the absence of antigen. This study is important because it explores the connection between mind and body, and resistance to disease. It has become increasingly apparent that many diseases are multifactoral, and psychosocial aspects may play an important role in the etiology of these diseases.